1. Field of the Invention
The invention relates to a method for the disposal of flexible material, which is in the form of at least one moving material web, which is fed in a feed direction with a feed web speed to a disposal device, particularly for disposing of used stamping film web during the operation of a hot stamping apparatus.
In hot stamping, in a hot stamping apparatus a material layer to be stamped is guided at a constant speed through a stamping gap, which is formed between a stamping cylinder having the stamping tool and a counterpressure or impression element, particularly an impression cylinder. Over the material layer a stamping film web is so concomitantly moved that it is displaced at the same speed as the material layer during a stamping interval. During the stamping interval, stamping material on the stamping film web, e.g. discreet, successive stamping units such as images or texts, or part of a colour layer to be stamped on is transferred to the material layer, under the action of pressure and temperature. Using a suitably constructed conveying mechanism, the stamping film web is drawn off of a preferably roll-like film supply and moved through the stamping gap, whilst the used stamping film is removed and has to be disposed of.
In known hot stamping devices of this type disposal takes place in that the used stamping film web is wound onto a wind-up storage roll. When the roll is full on the waste side, it is necessary to interrupt the stamping process or the feed to the waste roll for roll change purposes. This normally gives rise to machine downtimes reducing the overall stamping efficiency. In addition, on stopping the installation or restarting, malfunctions and/or waste production with respect to the stamped material can arise. In order to avoid such problems a continuous disposal of used web material is sought.
2. Description of Related Art
A stamping apparatus known from GB 2 254 586 has on the waste side a disposal device functioning in the manner of a shredder and which is supplied with the spent web material by means of an upstream conveying station. The latter has two contrarotating transfer rollers, between which the web material is jammed and conveyed through. The free web material end passing out of the conveying mechanism on the discharge side passes into the feed slot of the shredder, which tears the web material into small pieces and conveys same into a storage tank, which is emptied every so often. Particularly in the case of relatively thin, only slightly inherently rigid web material, malfunctions can arise in the cutting mechanism of shredders, e.g. as a result of incomplete tearing of the material or clogging of the cutting mechanism.
The problem of the invention is to avoid the disadvantages of the prior art. In particular, a method and an apparatus are to be provided, which permit a troublefree, continuous disposal of in particular also very thin web material, such as used stamping film web.
In order to solve this problem, the invention proposes
a method for the disposal of flexible material in the form of at least one moving material web, the material web being supplied in a feed direction with a feed web speed to a disposal apparatus, the method comprising the following steps:
holding fast a first web section of the material web the second web section being spaced from the first web section;
holding fast a second web section of the material web;
separation of the material web in an intermediate section located between the first web section and the second web section.
In addition, the invention proposes a disposal apparatus for the disposal of flexible material in the form of at least one moving material web, the material web being supplied in a feed direction with a feed web speed to the disposal apparatus, the disposal apparatus comprising:
first holding means for the retention of a first web section of the material web in a retention area;
second holding means for the retention of a second web section of the material web in a retention area, the first holding means being spaced apart from the second holding means;
a separating device cooperating with the holding means for separating of the material web in an intermediate section located between the first web section and the second web section.
According to the invention, in the case of a disposal method according to the preamble, a first material web section and a second material web section preferably laterally spaced from the first web section are held fast and that the material web in an intermediate section located between the first and second web sections is separated or cut through for producing web material pieces. The web material pieces can then be collected and optionally undergo further processing steps. As a result of the preferably flat or areal holding fast of the web material on either side of the separating area, it is possible to ensure that during the separation process the web material is not drawn into the separating area, i.e. does not give way to a preferably mechanically acting separating member and instead opposes the same with a resistance facilitating separation. This is particularly advantageous in the case of very thin web material having a limited inherent rigidity, such as e.g. stamping film webs, which have a typical thickness between 10 and 20 xcexcm. Such stamping film webs provided with a carrier film of tough plastic have a tendency in the cutting mechanisms of conventional shredders, whose cutting mechanisms have cutting rollers in cutting engagement with one another, due to inadequate film tension tend to be not or incompletely separated and/or to clog the cutting mechanisms. As a result of the inventive holding fast of the web material on either side of the separating or intermediate section, the web material is kept under tension in the separating section, which aids an easy, reliable and complete separation.
According to a further development, the web material is separated in an intermediate or separating section freely suspended and/or held taut between the stopped web sections. As a result it is possible to aid a complete separation, because a separating member used for separating purposes can completely pass through the surface area defined by the web material. To attain a reliable separation it is advantageous if the length of the freely suspended intermediate section, i.e. not in contact with a substrate, is kept as short as possible, so as to minimize the deflection aside of the web material during separation aided by the extension elasticity of the web material to be separated. The length of the free intermediate section can correspondingly be less than 1 cm, particularly between approximately 1 and approximately 5 mm.
According to a preferred development, the first web section is at the front in the feed direction and the second web section at the rear in the feed direction and that separation takes place transversely, particularly substantially perpendicular to the feed direction. In the case of this cross-separation normally taking place over the entire material web width, the web portion at the front can be separated and easily disposed of, whereas the rear portion can still be held and can serve as the front portion for the following separation. As a result of the holding fast of the in each case rear web section, it is also ensured that the supplied material web cannot slip out of the disposal device and is instead constantly securely held.
Alternatively or additionally, it is also possible, considered in the feed direction, for the first web section to at least zonally be positioned alongside the second web section and for the separation to take place at an acute angle or substantially parallel to the feed direction. As a result of a longitudinal cut or preferably several parallel, particularly simultaneously performed longitudinal cuts optionally narrow strips of web material can be produced, which can optionally be further shortened by suitable transverse cuts or tears. The resulting strips can remain, after separation, advantageously in areal contact with a conveying mechanism carrying them and can therefore be supplied in an ordered arrangement to further disposal stages.
For the complete separation of the web material it is possible to use various methods, which are preferably adapted to the separating or cutting method for the web material. Particular preference is given to a method in which the web material for complete separation is cut with a free cutter, i.e. with a mechanical separating member, which requires for bringing about the separating action no countermember, such as a counterblade or the like. Corresponding separating devices have a particularly long life and are subject to very little wear, because in particular with web material freely suspended in the separating area a blade only comes into contact with the softer web material. It is also possible to melt the web material in the intermediate area for separation purposes, particularly along a substantially straight melt line. This variant e.g. performable by means of a hot air blower or heated or incandescent wire or the like is particularly suitable for web material with a thermoplastic material. An advantageous variant is characterized in that, for separation, the web material is perforated at numerous, preferably linearly positioned points and preferably simultaneously and the perforations are subsequently enlarged until they coalesce. This method, e.g. performable by means of a pressed-on sawtooth blade is particularly suitable for the separation of plastic sheets, but as a result of the initial punctiform action of a separating member on the sheet web only requires limited forces for producing adequate separating pressures and can be used with particular advantage for taut web material, in which the enlargement of the perforations can in part be assisted by automatically progressing cracks in the taut material.
According to a further development, for holding fast purposes, a web section is pressed, whilst building up static or sliding friction, onto a pressure surface moving in the feed direction. Compared with an also possible, substantially punctiform or linear retention, the resulting large-area retention on a pressure surface of e.g. one or more square centimeters requires little force for a reliable hold. As a result of the areal application of the holding force, there is a reliable avoidance of material damage to the web material, which could lead to unintentional tears. It is particularly preferred if, for retaining a web section, between the latter and the pressure surface a vacuum is produced. A web section is so-to-speak held from below, whilst the side remote from the pressure surface remains free from holding means, so that a particularly large amount of space can be created for the application of a suitable separating device. A pressure surface can in particular be formed by an outer surface of a rotating conveying member of a suction conveyor, e.g. a suction belt, particularly a suction roller.
Disposal can include a step of collecting separated material pieces following the separating operation. Preference is given to a method in which, following separation, the web material pieces are detached from a moving pressure surface carrying and/or retaining the same. This can e.g. take place with contact by means of a spatula, doctor blade, etc., but is preferably performed in contactless manner by means of at least one air flow, which raises the web material portions from the pressure surface, particularly by suction. Blowing and sucking off can also be used in combination for separating purposes.
As a result of the continuous breaking down into pieces of the web material a space-saving packing of the used material is assisted, because no material pieces with higher packing densities have to be stored. The packing density can preferably be increased in that the collected web material pieces are compressed, preferably batchwise, e.g. to less than xc2xd, xc2xc or xe2x85x9 of the packing volume in the looser, uncompressed state. The waste e.g. compacted in a baling press can subsequently be stored in space-saving manner and/or transported away.
The invention permits a continuous disposal of used web material and in particular even in the case of thin films this takes place in a troublefree manner, so that stoppages resulting from disposal can be avoided and correspondingly the throughput capacity of the web material processing equipment can be increased.
A disposal apparatus suitable for performing the method has first holding means for the flat or areal holding fast of a first web section, second holding means for the flat or areal holding fast of a second web section, which is preferably laterally spaced from the first web section, and at least one separating device cooperating with the holding means for the separation of the web material in an intermediate or separating section located between the web sections.
Advantageously the first holding means and/or the second holding means have at least one pressure surface movable in the feed direction and onto which the web sections can be pressed flat. In particular, the holding means can be formed by a continuous, revolving conveying means, such as a conveyor belt or feed roller, on which a longitudinal section of the web material rests flat. It is possible for the pressure surface to be moved with the feed web speed, so that static friction can build up between the web material and the pressure surface. It is also possible to move the pressure surface at a higher speed or excess speed compared with the supplied material, so that slip occurs between the pressure surface and the material web, accompanied by the building up of sliding friction.
Pressure can be applied from the side opposite to the pressure surface, e.g. in material-protecting manner using brushes or the like. In a preferred embodiment the holding means are formed by a suction conveyor, particularly a suction roller, which has at least one conveying element rotating at the feed speed or a circumferential speed higher than the feed speed and having an outer surface serving as the pressure surface, onto which can be sucked a longitudinal web material section incorporating the web sections and the intermediate or separating section.
Although it is possible for an associated separating device to come into cutting engagement e.g. with the pressure surface, it is preferable for said pressure surface to have at least one recess, preferably running transversely to the movement direction and bridgeable or spannable by the web material. In the vicinity of the recess a section of the pressed on web material can be held in freely suspended and/or taut manner without contact with the substrate, which aids a reliable separation in this area.
A separating device preferably has at least one movable separating member controlled in such a way that it separates the moving web material in the vicinity of the recess bridged by the web material in freely suspended manner. In particular, the separating device can have at least one rotary member synchronized with the rotating conveying means and carrying on its circumference at least one separating member preferably oriented transversely to the circumferential direction and which is so positioned with respect to the conveying means, that a separating member meshes or engages in an associated recess. As a result of the separating member the web material freely suspended and optionally taut in the vicinity of the recess can be reliably and completely separated. A construction particularly suitable for cutting stamping film webs or other plastic films is characterized in that the separating member is a cutting blade, particularly having a serrated edge, through which punctiform perforations are initially formed even in the case of limited pressure action when the separating member engages in the web material and which, optionally assisted by the inherent tension of the web material, during further penetration of the cutting member are enlarged and finally coalesce so as to form a through cut.
Further features and details of the invention can be gathered from the following description of a preferred embodiment in conjunction with the drawing and subclaims. The individual features, either singly or in the form of combinations, can be implemented in an embodiment.